<?php

/**
 * @file
 * Database schema code for MySQL database servers.
 */


/**
 * @ingroup schemaapi
 * @{
 */

class DatabaseSchema_mysql extends DatabaseSchema {

	/**
	 * Maximum length of a table comment in MySQL.
	 */
	const COMMENT_MAX_TABLE = 60;

	/**
	 * Maximum length of a column comment in MySQL.
	 */
	const COMMENT_MAX_COLUMN = 255;

	/**
	 * Get information about the table and database name from the prefix.
	 *
	 * @return
	 *   A keyed array with information about the database, table name and prefix.
	 */
	protected function getPrefixInfo($table = 'default', $add_prefix = TRUE) {
		$info = array('prefix' => $this->connection->tablePrefix($table));
		if ($add_prefix) {
			$table = $info['prefix'] . $table;
		}
		if (($pos = strpos($table, '.')) !== FALSE) {
			$info['database'] = substr($table, 0, $pos);
			$info['table'] = substr($table, ++$pos);
		}
		else {
			$db_info = Database::getConnectionInfo();
			$info['database'] = $db_info['default']['database'];
			$info['table'] = $table;
		}
		return $info;
	}

	/**
	 * Build a condition to match a table name against a standard information_schema.
	 *
	 * MySQL uses databases like schemas rather than catalogs so when we build
	 * a condition to query the information_schema.tables, we set the default
	 * database as the schema unless specified otherwise, and exclude table_catalog
	 * from the condition criteria.
	 */
	protected function buildTableNameCondition($table_name, $operator = '=', $add_prefix = TRUE) {
		$info = $this->connection->getConnectionOptions();

		$table_info = $this->getPrefixInfo($table_name, $add_prefix);

		$condition = new DatabaseCondition('AND');
		$condition->condition('table_schema', $table_info['database']);
		$condition->condition('table_name', $table_info['table'], $operator);
		return $condition;
	}

	/**
	 * Generate SQL to create a new table from a Drupal schema definition.
	 *
	 * @param $name
	 *   The name of the table to create.
	 * @param $table
	 *   A Schema API table definition array.
	 * @return
	 *   An array of SQL statements to create the table.
	 */
	protected function createTableSql($name, $table) {
		$info = $this->connection->getConnectionOptions();

		// Provide defaults if needed.
		$table += array(
				'mysql_engine' => 'InnoDB',
				'mysql_character_set' => 'utf8',
		);

		$sql = "CREATE TABLE {" . $name . "} (\n";

		// Add the SQL statement for each field.
		foreach ($table['fields'] as $field_name => $field) {
			$sql .= $this->createFieldSql($field_name, $this->processField($field)) . ", \n";
		}

		// Process keys & indexes.
		$keys = $this->createKeysSql($table);
		if (count($keys)) {
			$sql .= implode(", \n", $keys) . ", \n";
		}

		// Remove the last comma and space.
		$sql = substr($sql, 0, -3) . "\n) ";

		$sql .= 'ENGINE = ' . $table['mysql_engine'] . ' DEFAULT CHARACTER SET ' . $table['mysql_character_set'];
		// By default, MySQL uses the default collation for new tables, which is
		// 'utf8_general_ci' for utf8. If an alternate collation has been set, it
		// needs to be explicitly specified.
		// @see DatabaseConnection_mysql
		if (!empty($info['collation'])) {
			$sql .= ' COLLATE ' . $info['collation'];
		}

		// Add table comment.
		if (!empty($table['description'])) {
			$sql .= ' COMMENT ' . $this->prepareComment($table['description'], self::COMMENT_MAX_TABLE);
		}

		return array($sql);
	}

	/**
	 * Create an SQL string for a field to be used in table creation or alteration.
	 *
	 * Before passing a field out of a schema definition into this function it has
	 * to be processed by _db_process_field().
	 *
	 * @param $name
	 *   Name of the field.
	 * @param $spec
	 *   The field specification, as per the schema data structure format.
	 */
	protected function createFieldSql($name, $spec) {
		$sql = "`" . $name . "` " . $spec['mysql_type'];

		if (in_array($spec['mysql_type'], array('VARCHAR', 'CHAR', 'TINYTEXT', 'MEDIUMTEXT', 'LONGTEXT', 'TEXT')) && isset($spec['length'])) {
			$sql .= '(' . $spec['length'] . ')';
		}
		elseif (isset($spec['precision']) && isset($spec['scale'])) {
			$sql .= '(' . $spec['precision'] . ', ' . $spec['scale'] . ')';
		}

		if (!empty($spec['unsigned'])) {
			$sql .= ' unsigned';
		}

		if (isset($spec['not null'])) {
			if ($spec['not null']) {
				$sql .= ' NOT NULL';
			}
			else {
				$sql .= ' NULL';
			}
		}

		if (!empty($spec['auto_increment'])) {
			$sql .= ' auto_increment';
		}

		// $spec['default'] can be NULL, so we explicitly check for the key here.
		if (array_key_exists('default', $spec)) {
			if (is_string($spec['default'])) {
				$spec['default'] = "'" . $spec['default'] . "'";
			}
			elseif (!isset($spec['default'])) {
				$spec['default'] = 'NULL';
			}
			$sql .= ' DEFAULT ' . $spec['default'];
		}

		if (empty($spec['not null']) && !isset($spec['default'])) {
			$sql .= ' DEFAULT NULL';
		}

		// Add column comment.
		if (!empty($spec['description'])) {
			$sql .= ' COMMENT ' . $this->prepareComment($spec['description'], self::COMMENT_MAX_COLUMN);
		}

		return $sql;
	}

	/**
	 * Set database-engine specific properties for a field.
	 *
	 * @param $field
	 *   A field description array, as specified in the schema documentation.
	 */
	protected function processField($field) {

		if (!isset($field['size'])) {
			$field['size'] = 'normal';
		}

		// Set the correct database-engine specific datatype.
		// In case one is already provided, force it to uppercase.
		if (isset($field['mysql_type'])) {
			$field['mysql_type'] = drupal_strtoupper($field['mysql_type']);
		}
		else {
			$map = $this->getFieldTypeMap();
			$field['mysql_type'] = $map[$field['type'] . ':' . $field['size']];
		}

		if (isset($field['type']) && $field['type'] == 'serial') {
			$field['auto_increment'] = TRUE;
		}

		return $field;
	}

	public function getFieldTypeMap() {
		// Put :normal last so it gets preserved by array_flip. This makes
		// it much easier for modules (such as schema.module) to map
		// database types back into schema types.
		// $map does not use drupal_static as its value never changes.
		static $map = array(
				'varchar:normal'  => 'VARCHAR',
				'char:normal'     => 'CHAR',

				'text:tiny'       => 'TINYTEXT',
				'text:small'      => 'TINYTEXT',
				'text:medium'     => 'MEDIUMTEXT',
				'text:big'        => 'LONGTEXT',
				'text:normal'     => 'TEXT',

				'serial:tiny'     => 'TINYINT',
				'serial:small'    => 'SMALLINT',
				'serial:medium'   => 'MEDIUMINT',
				'serial:big'      => 'BIGINT',
				'serial:normal'   => 'INT',

				'int:tiny'        => 'TINYINT',
				'int:small'       => 'SMALLINT',
				'int:medium'      => 'MEDIUMINT',
				'int:big'         => 'BIGINT',
				'int:normal'      => 'INT',

				'float:tiny'      => 'FLOAT',
				'float:small'     => 'FLOAT',
				'float:medium'    => 'FLOAT',
				'float:big'       => 'DOUBLE',
				'float:normal'    => 'FLOAT',

				'numeric:normal'  => 'DECIMAL',

				'blob:big'        => 'LONGBLOB',
				'blob:normal'     => 'BLOB',
		);
		return $map;
	}

	protected function createKeysSql($spec) {
		$keys = array();

		if (!empty($spec['primary key'])) {
			$keys[] = 'PRIMARY KEY (' . $this->createKeysSqlHelper($spec['primary key']) . ')';
		}
		if (!empty($spec['unique keys'])) {
			foreach ($spec['unique keys'] as $key => $fields) {
				$keys[] = 'UNIQUE KEY `' . $key . '` (' . $this->createKeysSqlHelper($fields) . ')';
			}
		}
		if (!empty($spec['indexes'])) {
			foreach ($spec['indexes'] as $index => $fields) {
				$keys[] = 'INDEX `' . $index . '` (' . $this->createKeysSqlHelper($fields) . ')';
			}
		}

		return $keys;
	}

	protected function createKeySql($fields) {
		$return = array();
		foreach ($fields as $field) {
			if (is_array($field)) {
				$return[] = '`' . $field[0] . '`(' . $field[1] . ')';
			}
			else {
				$return[] = '`' . $field . '`';
			}
		}
		return implode(', ', $return);
	}

	protected function createKeysSqlHelper($fields) {
		$return = array();
		foreach ($fields as $field) {
			if (is_array($field)) {
				$return[] = '`' . $field[0] . '`(' . $field[1] . ')';
			}
			else {
				$return[] = '`' . $field . '`';
			}
		}
		return implode(', ', $return);
	}

	public function renameTable($table, $new_name) {
		if (!$this->tableExists($table)) {
			throw new DatabaseSchemaObjectDoesNotExistException(t("Cannot rename %table to %table_new: table %table doesn't exist.", array('%table' => $table, '%table_new' => $new_name)));
		}
		if ($this->tableExists($new_name)) {
			throw new DatabaseSchemaObjectExistsException(t("Cannot rename %table to %table_new: table %table_new already exists.", array('%table' => $table, '%table_new' => $new_name)));
		}

		$info = $this->getPrefixInfo($new_name);
		return $this->connection->query('ALTER TABLE {' . $table . '} RENAME TO `' . $info['table'] . '`');
	}

	public function dropTable($table) {
		if (!$this->tableExists($table)) {
			return FALSE;
		}

		$this->connection->query('DROP TABLE {' . $table . '}');
		return TRUE;
	}

	public function addField($table, $field, $spec, $keys_new = array()) {
		if (!$this->tableExists($table)) {
			throw new DatabaseSchemaObjectDoesNotExistException(t("Cannot add field %table.%field: table doesn't exist.", array('%field' => $field, '%table' => $table)));
		}
		if ($this->fieldExists($table, $field)) {
			throw new DatabaseSchemaObjectExistsException(t("Cannot add field %table.%field: field already exists.", array('%field' => $field, '%table' => $table)));
		}

		$fixnull = FALSE;
		if (!empty($spec['not null']) && !isset($spec['default'])) {
			$fixnull = TRUE;
			$spec['not null'] = FALSE;
		}
		$query = 'ALTER TABLE {' . $table . '} ADD ';
		$query .= $this->createFieldSql($field, $this->processField($spec));
		if ($keys_sql = $this->createKeysSql($keys_new)) {
			$query .= ', ADD ' . implode(', ADD ', $keys_sql);
		}
		$this->connection->query($query);
		if (isset($spec['initial'])) {
			$this->connection->update($table)
			->fields(array($field => $spec['initial']))
			->execute();
		}
		if ($fixnull) {
			$spec['not null'] = TRUE;
			$this->changeField($table, $field, $field, $spec);
		}
	}

	public function dropField($table, $field) {
		if (!$this->fieldExists($table, $field)) {
			return FALSE;
		}

		$this->connection->query('ALTER TABLE {' . $table . '} DROP `' . $field . '`');
		return TRUE;
	}

	public function fieldSetDefault($table, $field, $default) {
		if (!$this->fieldExists($table, $field)) {
			throw new DatabaseSchemaObjectDoesNotExistException(t("Cannot set default value of field %table.%field: field doesn't exist.", array('%table' => $table, '%field' => $field)));
		}

		if (!isset($default)) {
			$default = 'NULL';
		}
		else {
			$default = is_string($default) ? "'$default'" : $default;
		}

		$this->connection->query('ALTER TABLE {' . $table . '} ALTER COLUMN `' . $field . '` SET DEFAULT ' . $default);
	}

	public function fieldSetNoDefault($table, $field) {
		if (!$this->fieldExists($table, $field)) {
			throw new DatabaseSchemaObjectDoesNotExistException(t("Cannot remove default value of field %table.%field: field doesn't exist.", array('%table' => $table, '%field' => $field)));
		}

		$this->connection->query('ALTER TABLE {' . $table . '} ALTER COLUMN `' . $field . '` DROP DEFAULT');
	}

	public function indexExists($table, $name) {
		// Returns one row for each column in the index. Result is string or FALSE.
		// Details at http://dev.mysql.com/doc/refman/5.0/en/show-index.html
		$row = $this->connection->query('SHOW INDEX FROM {' . $table . "} WHERE key_name = '$name'")->fetchAssoc();
		return isset($row['key_name']);
	}

	public function addPrimaryKey($table, $fields) {
		if (!$this->tableExists($table)) {
			throw new DatabaseSchemaObjectDoesNotExistException(t("Cannot add primary key to table %table: table doesn't exist.", array('%table' => $table)));
		}
		if ($this->indexExists($table, 'PRIMARY')) {
			throw new DatabaseSchemaObjectExistsException(t("Cannot add primary key to table %table: primary key already exists.", array('%table' => $table)));
		}

		$this->connection->query('ALTER TABLE {' . $table . '} ADD PRIMARY KEY (' . $this->createKeySql($fields) . ')');
	}

	public function dropPrimaryKey($table) {
		if (!$this->indexExists($table, 'PRIMARY')) {
			return FALSE;
		}

		$this->connection->query('ALTER TABLE {' . $table . '} DROP PRIMARY KEY');
		return TRUE;
	}

	public function addUniqueKey($table, $name, $fields) {
		if (!$this->tableExists($table)) {
			throw new DatabaseSchemaObjectDoesNotExistException(t("Cannot add unique key %name to table %table: table doesn't exist.", array('%table' => $table, '%name' => $name)));
		}
		if ($this->indexExists($table, $name)) {
			throw new DatabaseSchemaObjectExistsException(t("Cannot add unique key %name to table %table: unique key already exists.", array('%table' => $table, '%name' => $name)));
		}

		$this->connection->query('ALTER TABLE {' . $table . '} ADD UNIQUE KEY `' . $name . '` (' . $this->createKeySql($fields) . ')');
	}

	public function dropUniqueKey($table, $name) {
		if (!$this->indexExists($table, $name)) {
			return FALSE;
		}

		$this->connection->query('ALTER TABLE {' . $table . '} DROP KEY `' . $name . '`');
		return TRUE;
	}

	public function addIndex($table, $name, $fields) {
		if (!$this->tableExists($table)) {
			throw new DatabaseSchemaObjectDoesNotExistException(t("Cannot add index %name to table %table: table doesn't exist.", array('%table' => $table, '%name' => $name)));
		}
		if ($this->indexExists($table, $name)) {
			throw new DatabaseSchemaObjectExistsException(t("Cannot add index %name to table %table: index already exists.", array('%table' => $table, '%name' => $name)));
		}

		$this->connection->query('ALTER TABLE {' . $table . '} ADD INDEX `' . $name . '` (' . $this->createKeySql($fields) . ')');
	}

	public function dropIndex($table, $name) {
		if (!$this->indexExists($table, $name)) {
			return FALSE;
		}

		$this->connection->query('ALTER TABLE {' . $table . '} DROP INDEX `' . $name . '`');
		return TRUE;
	}

	public function changeField($table, $field, $field_new, $spec, $keys_new = array()) {
		if (!$this->fieldExists($table, $field)) {
			throw new DatabaseSchemaObjectDoesNotExistException(t("Cannot change the definition of field %table.%name: field doesn't exist.", array('%table' => $table, '%name' => $field)));
		}
		if (($field != $field_new) && $this->fieldExists($table, $field_new)) {
			throw new DatabaseSchemaObjectExistsException(t("Cannot rename field %table.%name to %name_new: target field already exists.", array('%table' => $table, '%name' => $field, '%name_new' => $field_new)));
		}

		$sql = 'ALTER TABLE {' . $table . '} CHANGE `' . $field . '` ' . $this->createFieldSql($field_new, $this->processField($spec));
		if ($keys_sql = $this->createKeysSql($keys_new)) {
			$sql .= ', ADD ' . implode(', ADD ', $keys_sql);
		}
		$this->connection->query($sql);
	}

	public function prepareComment($comment, $length = NULL) {
		// Work around a bug in some versions of PDO, see http://bugs.php.net/bug.php?id=41125
		$comment = str_replace("'", '’', $comment);

		// Truncate comment to maximum comment length.
		if (isset($length)) {
			// Add table prefixes before truncating.
			$comment = truncate_utf8($this->connection->prefixTables($comment), $length, TRUE, TRUE);
		}

		return $this->connection->quote($comment);
	}

	/**
	 * Retrieve a table or column comment.
	 */
	public function getComment($table, $column = NULL) {
		$condition = $this->buildTableNameCondition($table);
		if (isset($column)) {
			$condition->condition('column_name', $column);
			$condition->compile($this->connection, $this);
			// Don't use {} around information_schema.columns table.
			return $this->connection->query("SELECT column_comment FROM information_schema.columns WHERE " . (string) $condition, $condition->arguments())->fetchField();
		}
		$condition->compile($this->connection, $this);
		// Don't use {} around information_schema.tables table.
		$comment = $this->connection->query("SELECT table_comment FROM information_schema.tables WHERE " . (string) $condition, $condition->arguments())->fetchField();
		// Work-around for MySQL 5.0 bug http://bugs.mysql.com/bug.php?id=11379
		return preg_replace('/; InnoDB free:.*$/', '', $comment);
	}

	public function tableExists($table) {
		// The information_schema table is very slow to query under MySQL 5.0.
		// Instead, we try to select from the table in question.  If it fails,
		// the most likely reason is that it does not exist. That is dramatically
		// faster than using information_schema.
		// @link http://bugs.mysql.com/bug.php?id=19588
		// @todo: This override should be removed once we require a version of MySQL
		// that has that bug fixed.
		try {
			$this->connection->queryRange("SELECT 1 FROM {" . $table . "}", 0, 1);
			return TRUE;
		}
		catch (Exception $e) {
			return FALSE;
		}
	}

	public function fieldExists($table, $column) {
		// The information_schema table is very slow to query under MySQL 5.0.
		// Instead, we try to select from the table and field in question. If it
		// fails, the most likely reason is that it does not exist. That is
		// dramatically faster than using information_schema.
		// @link http://bugs.mysql.com/bug.php?id=19588
		// @todo: This override should be removed once we require a version of MySQL
		// that has that bug fixed.
		try {
			$this->connection->queryRange("SELECT $column FROM {" . $table . "}", 0, 1);
			return TRUE;
		}
		catch (Exception $e) {
			return FALSE;
		}
	}

}

/**
 * @} End of "ingroup schemaapi".
 */
